The present invention relates generally to embolic protection devices. More specifically, the present invention pertains to catheter-based devices for trapping emboli, tissue, arterioschlerotic plaque or other particulate matter in the bloodstream. During angioplasty and stent implantation procedures, oftentimes emboli or other particulate matter is dislodged from the vascular wall. Once dislodged, this particulate matter enters the bloodflow and, unless trapped, collected and removed from the body in some fashion, poses a serious risk to the patient.
Conventional embolic protection devices typically employ umbrella-like baskets in which structural support members are fabricated of elastically strained segments, such as stainless steel or nitinol wire or hypotubing, and rely upon the relative antegrade and retrograde movement of coaxial shafts of a catheter member to deploy and collapse the embolic basket in a manner similar to the way an umbrella is opened and closed. One disadvantage of these umbrella-like devices is increased profile because the material forming the embolic basket must be folded in some manner when the basket is not deployed. Another disadvantage of umbrella-like devices is the excess flap material comprising the embolic basket when under-deployed will fold and invaginate into the lumen of the vessel causing poor apposition between the vessel wall and embolic basket.
Moreover, conventional embolic protection devices are typically fashioned of materials having a relatively constant open surface area across the surface area of the embolic basket. The structure of the embolic basket in conventional embolic protection devices is such that the open spaces are dimensioned to capture emboli or other particulate matter of a certain size that are dislodged as a result, for example, of the angioplasty or stent implantation procedure. With conventional embolic protection devices, the design of the device anticipates that a certain fraction of emboli or particulate matter will pass through the device and into the patient""s general circulation.
In accordance with one aspect of the invention, an embolic protection device comprising a first elongate member having a lumen, a second elongate member extending through the lumen and being movable with respect to the first elongate member, a graft member having a proximal end portion connected to the first elongate member and a distal end portion connected to the second elongate member, and a plurality of openings extending through the graft member along a length thereof is provided. The graft member is expandable from an undeployed generally tubular state to a deployed generally frustroconical state upon relative movement between the first and second elongate members in a first direction. The openings generally decrease in size from the proximal end toward the distal end when the graft member is in the deployed state to thereby capture and retain emboli and other particulate matter of different sizes.
In accordance with a further aspect of the invention, an embolic protection device comprises a catheter body having a central longitudinal lumen, a guidewire having an atraumatic tip positioned at a distal end thereof, and a graft member movable between an undeployed state and a deployed state. The guidewire is coaxially positioned within the central longitudinal lumen of the catheter body. The graft member is preferably of a generally tubular shape in the undeployed state and of a generally frustroconical shape in the deployed state. The graft member has a plurality of openings that extend along a length thereof. A plurality of arm members interconnect a proximal end of the graft member and the catheter body. A distal end of the graft member is connected to one of the guidewire and the atraumatic tip. The graft member is movable between the undeployed and deployed states upon relative movement between the catheter body and the guide wire. Preferably, the graft member is constructed of a material such that each opening expands or reduces in size in proportion to an amount of radial expansion or reduction, respectively, of a corresponding transverse cross sectional region of the graft member with which the opening is associated, to thereby capture emboli and other particulate matter when the graft member is in the deployed state and minimize extrusion of the captured material through the openings in the graft member when the graft member is in the undeployed state.